Chapter 26, Problem 6RQ

How did seismic waves contribute to the discovery of Earth’s core?

To determine

The contribution of seismic waves in the discovery of Earth’s core.

Answer to Problem 6RQ

The seismic waves helped to discover the different composition of Earth’s core. The motion of P-waves and S-waves evidenced that the core has two parts, inner core and outer core.

Explanation of Solution

The seismograph shows that the S-waves traveling through the core travels a certain distance and then stops, but the P-waves travels same distance but do not stop rather gets refracted and lost their speed. This happened at the boundary of the core and mantle, which is approximately 2900 km.

At the boundary of core and mantle, P-waves reflect and refract and casts a shadow where no waves are detected. The boundary of core and mantle is distinct in the seismograph due to the visible variation.

The core is separated into two parts, the inner core and outer core. The inner core consists of solid iron in which S-waves and P-waves both travel and also P-waves gain speed in this region. The outer core is the molten iron core in which S-waves cannot travel and P-waves lose their speed and refract.

Conclusion:

Therefore, The seismic waves helped to discover the different composition of Earth’s core. The motion of P-waves and S-waves evidenced that the core has two parts, inner core and outer core.